Fuel Injector – Deposits Can Build Up And Clog The Fuel Injector

Fuel injector deposits and failure symptoms. Gasoline is a mixture of many different hydrocarbons, including oilfins, which are heavy, waxy compounds.

When the engine is off, there is no cooling airflow through the ports and no fuel flow through the fuel injector to wash it away, so heat bakes the oilfins into hard varnish deposits.

Therefore over time, these deposits can build up and clog the fuel injector. Furthermore the formation of these deposits is a normal consequence of engine operation. In addition detergents are added to gasoline to help keep the injectors clean.

But if a vehicle is used primarily for short-trip driving, the deposits may build up faster than the detergents can wash them away.

On four-cylinder engines, the #2 and #3 injectors are in the hottest location and tend to clog up faster than the end injectors on cylinders #1 and #4. Hence the same applies to the injectors in the middle cylinders in six- and eight-cylinder engines.

As a result the hotter the location, the more vulnerable the injector is to clogging from heat soak. Throttle body injectors are less vulnerable to heat soak because of their location high above the intake manifold plenum.

Fuel Injector Spray Patterns
Fuel Injector Spray Patterns

Fuel injector deposits and failure symptoms.

  • Starting issues
  • Poor idle
  • Failed emissions
  • Poor Performance
  • Engine does not reach full RPM
  • Increased fuel consumption
  • Rough engine performance
  • Surging and bucking under various throttle loads
  • Smoke from the tailpipe
  • Not to mention Engine Knock or Detonation which can lead to catastrophic engine failure
  • Pollution

In addition other signs and issues to watch for include:

  • Restrictions
  • Turbo Troubles
  • Heat Soak
  • Also Increase or Decrease in Long- and Short-Term Fuel Trims
  • Not Enough Resistance
  • Longer Crank Times
  • Failed Balance Tests
  • Misfire Codes
  • Vehicle Won’t Start With Full Tank
  • Lack of Maintenance
Firing Fuel Injector
Firing Fuel Injector

In conclusion being able to observe these symptoms is an important aspect of realizing that there is a problem with a car, and being able to associate these symptoms with specific fuel injector problems will help car owners to resolve the issues with their injectors quickly.


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